Sporting Kansas City prided itself on having the top defense in Major League Soccer last season.

The club set myriad team records for stinginess, including fewest goals allowed (27) and best goals-against average (0.79), during its run to a second straight Eastern Conference regular-season crown.

It’s been a considerably rockier start to 2013 for Sporting KC, which was lucky to concede only one goal in the opening 35 minutes at the Philadelphia Union and fell behind 2-0 in the opening 20 minutes a week later at Toronto FC.

When discussing his squad’s leaky defense, manager Peter Vermes cited the four pillars of soccer.

“It’s not technical. It’s not tactical. It’s not physical,” he said. “It’s a psychological thing — and it’s something that has to change.”

While it’s worth pointing out that the Union and Toronto were both playing their home openers in front of rowdy, energetic crowds, that doesn’t excuse the sluggish starts to either game.

“Other teams have started with a lot of energy, but it’s our fault we haven’t matched it,” reigning MLS defender of the year Matt Besler said. “There’s no reason why we can’t come out on fire and intense away from home. That’s what should happen and what needs to happen.”

Sporting KC, 1-1-0, managed to rally for a 3-1 win in the opener against the Union but couldn’t claw back after the wretched start in Toronto — a game that featured an uncharacteristic blunder by Besler that led to the first goal off a soft pass across the top of the box to a backpedaling Aurelien Collin.

Reigning MLS goalkeeper of the year and Sporting KC captain Jimmy Nielsen called watching the Toronto loss a depressing endeavor.

“The way we defended on the whole field in the first half is not how we defend … (and) it’s everything,” Nielsen said. “You’ve got to be quicker getting into position and take the bites. You can’t wait and wait and wait. You’ve got to step in there and avoid the cross coming or shot on goal. You’ve got to smell the game, too. When is it time to play the possession game and when is it time to battle?”

There are plenty of new faces — forward Claudio Bieler, midfielder Benny Feilhaber and defensive midfielder Uri Rosell — in the starting lineup, which throws off the chemistry established last season.

However, missing two of last season’s toughest defenders — the frenetic midfield presence of Roger Espinoza and the veteran savvy Julio Cesar brought in front of the back line — can’t be dismissed.

Sporting KC needs Espinoza’s replacement, Paulo Nagamura, to become disruptive and ever-present in unsettling the opposing attack, while Rosell — who is a much more proficient passer and reads the game well, but is also more offensive-minded than Cesar was — continues to settle in.

“We’re trying to find our rhythm, the rhythm of how we’re going to play as a team,” Besler said. “Obviously, there are some new faces in there and unfortunately it hasn’t been perfect the first two games, but the season is really long and we have time. We’re going to get it figured out.”

In both games, Sporting KC emerged from the halftime locker room playing the ferocious brand of soccer for which it wants to be known.

Of course, that only made the first-half struggles more frustrating.

“We haven’t clicked yet for 90 minutes, but there have been glimpses of it,” Besler said. “Look at the second halves of each game. Those were pretty complete halves, but now we have to put two together in a single game.”

Perhaps that will happen Saturday when Sporting KC welcomes the Chicago Fire for a 2 p.m. kickoff in its home opener at Sporting Park. The game will be broadcast on NBC Sports as part of its Rivalry Day.